Junko Ishido, mother of Kenji Goto, a Japanese journalist being held captive by Islamic State militants along with another Japanese citizen, reacts during a news conference at the Foreign Correspondents' Club of Japan in Tokyo January 23, 2015 (Reuters / Toru Hanai) / Reuters

The devastated mother of a Japanese journalist held captive by the Islamic State has begged for her son's release. Militants affiliated with the group have warned the "countdown has begun" to kill two Japanese hostages.

The online posting which appeared on Friday features a clock
counting down to zero along with gruesome images of other
hostages beheaded by the Islamic State militant group. Nippon
Television Network first reported the message in Japan.

The devastated mother of a Japanese journalist held captive by
the Islamic State has pleaded for her son's release. It came just
hours before militants pledged to execute the man unless Tokyo
pays a $200m ransom.

ISIS is threatening to behead Japanese citizens. Obama says
they're on the run. But he won twice! Sick burn, bro! pic.twitter.com/iuTH9ELtSV

Junko Ishido has called on the government to rescue her son,
Kenji Goto, a 47-year-old war correspondent with experience in
Middle East hot spots. He went to Syria in October to try to
negotiate the release of his fellow captive Haruna Yukawa, a
security consultant who was captured by the Islamic State (IS,
formerly ISIS/ISIL) last August outside the Syrian city of
Aleppo. The two Japanese men first met in Syria last April.

“That’s how compassionate Kenji is, having always cared for
his weak friends,” Ishido said. "If I could offer my
life I would plead that my son be released, it would be a small
sacrifice on my part," Goto's mother told a packed news
conference on Friday, unable to hold back tears. She said her son
had left his two-week-old baby behind to travel to Syria, because
"he had to do everything in his power to save his friend and
acquaintance."

Mrs Goto voiced hopes that Prime Minister Shinzo Abe would follow
in the footsteps of Prime Minister Takeo Fukuda, who paid a $6
million ransom to the Japanese Red Army radical group, whose
members sought to overthrow the government, and hijacked a Japan
Airlines flight en route from Tokyo to Paris in 1977.

Fukuda came under intense fire, with many accusing him of caving
in to terrorists.

“To the people of the Japanese government, please save
Kenji’s life,” Ishido said, speaking at the Foreign
Correspondents’ Club of Japan in Tokyo, the Japan Times reported.

In an online video released on Tuesday, a British-sounding
militant is seen holding a knife while standing between Kenji
Goto and Haruna Yukawa, threatening to kill them if Tokyo did not
pay the Islamic State $200 million within 72 hours.

The IS deadline for the ransom passed on Friday, with the fate of
the captives currently unknown. Prior to the video's release,
Japanese diplomats had told the families of the two captives that
the government wouldn’t pay any ransom, Reuters reported, citing
a source close to the matter.

Abe told the government to make an all-out effort to secure the
captives' safe release. "The government is continuing to work
in unison to gather information and make every efforts for their
release," Chief Cabinet Secretary Yoshihide Suga told a news
conference, adding that the government is in an "extremely severe
situation." Asked if Tokyo would pay the ransom, he said there's
"no change to our stance that we will not give in to
terrorism and will contribute to the international response to
terrorism."

Meanwhile, Tokyo's key mosque, the Tokyo Camii and Turkish
Culture Center, has posted a statement calling for the prompt
release of the hostages. It said the Islamic State's actions are
"totally against Islam and have a serious impact on Muslim
communities all over the world and put Muslims in a precarious
position."

"My son Kenji is not an enemy of the people of the Islamic
faith," Junko Ishido said.